Why Marine Heatwaves Spell Trouble For Tropical Fish

As the global climate crisis continues to ravage the world, heatwaves caused by it are starting to hit our oceans, spelling trouble for tropical marine wildlife and economically important aquatic ecosystems.

Why Heatwaves Spell Trouble For Tropical Fish

Despite the numerous troubles that are our oceans are going through today, the waters remain steadfast and strong and coral reefs continue to be strongholds for underwater biodiversity, constantly adapting and thriving with the times. As such, thousands of fish species and other aquatic animals call these natural ecosystems home in a give-and-take relationship that has always benefitted both parties.

However, it seems like trouble is brewing for these tropical fish, all thanks to the heatwaves caused by the global climate crisis. A new study, published in Ecological Applications, explores this.

Heating Up The Waters

Made while surveying Kiritimati, or the world’s largest coral atoll (ring-shaped reef), the researchers tried to find out what would happen if tropical fish go through unprecedented levels of continuous heat stress for 10 straight months (which happened during the 2015-16 El Niño). The results were devastating.

Per the team, reef fish populations around the atoll had managed to go down by half after just two months of heat stress, with some of the species disappearing completely. Five species, which includes the Chevron butterflyfish, had not been seen since.

Surprisingly, however, the total reef fish biomass and abundance had managed to recover after a year. So what happened during those heat-stricken months?

Per the research, the disappearance of some species during these hotter months most likely happened because they sought out shelter in cooler waters, going back to the shallows after the heat has passed. However, not all parts of the atoll were able to recover. Considering that a lot of communities depend on these fish for survival, it’s safe to say that their short-term disappearance is a big deal.

As such, local environmental protection should make efforts to help make coral reefs more resilient to severe ocean warming since the heatwaves not only affect the homes, but the aquatic inhabitants as well.

coralreef A protein that blocks HIV from attaching to the body's T cells was discovered off the coast of Australia. USFWS - Pacific Region, CC BY 2.0